BoilerFaultCodesThe 6 most common faults
Your boiler has stopped running because the water inside it has become hotter than the temperature you have requested.
Why it happens: This fault occurs when water is staying inside the boiler's heat exchanger for too long, causing it to overheat beyond the safe limit. The most common reasons are a pump failure that prevents water from moving around your radiators, or a blockage such as trapped air or sludge that is restricting the flow. Because the heat cannot be carried away from the boiler quickly enough, the system shuts down as a safety precaution.
Check that your radiator valves are open to allow water to circulateEnsure there is no air trapped in your radiators by bleeding themCheck that the boiler pressure gauge is between 1 and 1.5 barReset the boiler to see if the fault clears
Your boiler has switched itself off because it has detected it is getting too hot, usually caused by the water pressure being too low.
Why it happens: This fault occurs when the internal safety sensor detects that the heat exchanger has become dangerously hot, causing the boiler to shut down to prevent damage. The most common reason is a lack of water circulating through the system, often due to low pressure, a blockage, or a pump failure. If there isn't enough water to carry the heat away to your radiators, the temperature inside the unit rises too quickly.
Check the pressure gauge on the front of the boiler or the digital display.Locate the filling link (usually a blue lever underneath the boiler or a white plastic key).Slowly top up the water pressure until it reaches between 1.0 and 1.5 bar.Press the 'Reset' button on the boiler display to clear the fault.
Your boiler is failing to light the flame properly, meaning you will not have any heating or hot water until the issue is resolved.
Why it happens: This fault occurs when the boiler's internal computer tries to start a fire but cannot detect a stable flame. The most common reasons are a lack of gas reaching the burner, dirty sensors failing to 'see' the flame, or a fault within the electronic control board that manages the ignition process.
Check if your gas supply is working by testing other gas appliances like a hobEnsure your gas meter has credit if you use a pre-payment meterPress the Reset button on the boiler display panel once to attempt a restart
Your boiler has stopped working because the water pressure is too low and needs to be topped up.
Why it happens: This fault occurs when the system loses too much water, preventing the boiler from circulating heat safely. The most common reasons are a slow leak from a radiator valve or the natural loss of pressure that happens after you bleed your radiators. If the pressure looks normal on the gauge but the code persists, the internal sensor that reads the water level may be blocked or broken.
Locate the integrated filling link (blue levers) or the external filling loop underneath the boilerSlowly open the valves until you hear water moving and watch the digital display or pressure gaugeClose the valves firmly once the pressure reaches between 1.0 and 1.5 bar
Your boiler has detected that water is not moving through its internal heating unit fast enough, which can cause the system to overheat and shut down.
Why it happens: This fault occurs when water is unable to circulate through the boiler's main heat exchanger at the required speed to safely carry heat away. The most common reasons are a failing internal pump, a build-up of sludge or debris blocking the pipework, or a secondary heat exchanger that has become restricted over time.
Check that your system pressure is between 1 and 1.5 bar on the front displayEnsure all radiator valves are fully open to allow water to circulateInspect the magnetic system filter, if fitted, to see if it needs cleaning
Your boiler has shut down because the water inside is getting much hotter than it should be, which is often caused by a blockage or a pump failure preventing the heat from moving away.
Why it happens: This fault happens when the water leaving the boiler heats up too quickly or exceeds safe limits, causing the system to shut down for safety. It is usually caused by a pump failure or a blockage within the pipes that prevents hot water from circulating away from the boiler's heat exchanger. In many cases, it is the result of 'sludge' or debris building up over time and restricting the flow of water.
Check that all radiator valves are fully open to allow water to circulate.Ensure your boiler pressure gauge is between 1 and 1.5 bar; top up if necessary.Check if any external bypass valves or magnetic system filters are blocked.
on the Worcester Bosch Greenstar 8000 Life/Style
Based on parts cited in our fault code database. Your engineer will confirm what's actually needed after diagnosis.
Call a Gas Safe engineer if…
- You can smell gas or see signs of a leak
- The Worcester Bosch shows an Emergency or High severity code
- The boiler keeps locking out after repeated resets
- You've tried the DIY checks and the fault hasn't cleared
- There's visible water leaking from the boiler
- The flame is yellow or orange instead of blue